>In Malaysia we have a popular script (Jawi) which resembles the Arabic
>script, except for a
>missing character. I've read the document on www.unicode.org on procedure
>of how to submit new
>characters to the Unicode Standard.
>
>The missing character is called "ga" (attached). It looks like Kaf (06A9)
>with a dot on top. I
>have 2 options: ...

In Arabic fonts I have been involved with, we have treated this as a Jawi
glyph variant of gaf (U+06AF). This follows the practice established in
Linotype's metal, photo and early digital Jawi fonts. In more recent,
OpenType format fonts, we have provided the Jawi variant as an unencoded
glyph, mapped to the regular gaf using the Localised Forms <loca> feature
associated with the Malay language system. System support for language
system-specific glyph substitution is still in development, but this model
will eventually provide what you need.

That said, I don't claim to know whether treating this letter as a glyph
variant of U+06AF is the best approach, or whether it might be better
handled as a distinct character.

If meaning is inherently public and rule-governed, then the
fact that I can't read 'Treasure Island' without visualising
Long John Silver as a one-legged version of my grandmother
is of interest only to my psychotherapist and myself.
Terry Eagleton